For various reasons crops sometimes are lying so close to the ground that it is difficult to cut them with a conventional harvest header. Some crops are inherently short, while others may be taller, but are prone to fall down when they reach maturity. Heavy rain or hail can also cause crop to be lying close to the ground at harvest time.
Typically the knife on cutting headers comprises a knife bar extending along the front lower edge of the header, with a plurality of triangular knife sections attached to the bar such that the apex of the triangle extends forward from the bar. The exposed side edges of the knife sections are sharpened. Guards are attached to the front lower edge of the header and serve to protect the knife sections from breakage when contacting stones and like obstructions. The guards comprise pointed guard fingers extending forward, and the knife moves back and forth along the edge of the header in a slot cut laterally through the guard fingers. In addition to protecting the knife, the guard fingers also enable the knife sections to cut the crop. As the knife section moves back and forth it pushes crop against the sides of those portions of the guard finger that are above and below the slot, shearing the crop stalks.
A conventional knife is a few inches above the ground when the header is in its lowest position, such that very short or downed crop material will pass under the knife and be lost. Many different kinds of “crop lifters”, as they have come to be known have been developed over the last century and more. Typically these crop lifters are attached to the header and/or the forward extending point of the guard finger, and provide an arm of various designs that rides along the ground ahead of the knife. A lifting finger extends at a shallow angle from the front of the arm back and over the knife. As the header moves down the field, the arm rides along the ground and under the downed crop stalks, which then are lifted and pass over the lifting finger to the knife, where they are cut and continue moving onto the header from where they can be passed to the harvester, swather table, or the like.
U.S. Pat. Nos. 700,029 and 791,022 to Gatermann, 2,734,332 to Fisher, 2,892,298 to Chaney, 2,960,814 to Babcock, and Canadian Patent Number 407,654 to Young disclose such a crop lifter that is pivotally attached to the header so as to be able to move up and down to follow the ground. The Babcock and Fisher devices float on the ground, while the others are biased toward the ground by springs. U.S. Pat. No. 4,120,138 to Schumacher illustrates a crop lifter that is fixed to the header instead of pivoting, but is made of spring steel so that same may move up and down to follow the ground.
The leading ends of the lifting fingers on these devices is fixed in relation to the arm such that the leading end is at a fixed distance above the ground, but quite close to the ground in order to lift as much crop as possible. Generally speaking crop stalks that pass under the leading end will be lost, and those that pass over will be harvested.
Most commonly in the prior art the leading end of the lifting finger is generally the leading end of the arm, and is therefore upturned to provide a ski effect and ride over the ground instead of digging in. In the Chaney and Fisher devices, the leading end is ahead of the arm and is pointing generally down very close to the ground to collect the lowest lying crop possible. In the Fisher device, an adjustment is provided to vary the angle of the lift finger, and the lift finger can also be longitudinally adjusted relative to the arm to vary the distance from the leading end of the lifting finger to the ground.
If even a small obstruction is contacted by the Chaney or Fisher devices, they will not ride over it, but will be required to push it to the side, making them more subject to damage. A problem with conventional lifters of substantially all types is that breakage, bending, and deformation is not uncommon as a result of contact with obstructions or ground variations in the field. Repair of such damage is time consuming, requiring removal of the bolts or like fasteners attaching the lifter, and repair if possible by straightening with a press, welding, or the like. Often replacement is necessary at fairly significant expense.
Demonstrating another alternative crop lifter, United States Patent Application Publication 2001/0037635 of Figliuzzi discloses a crop lifter that provides a lifting finger that extends rearward and upward from the point of a guard finger. In one illustrated embodiment the point of the guard finger is extended substantially forward from a conventional location.
Generally cutting headers are used in taller crops as well as on the short and downed crops described above. In such crops the header is raised a substantial distance above the ground. Often in such taller crops however there will be crop stalks that have fallen over due to insect damage, weather, or the like and are closer to the ground than the desired cutting height. It is problematic to operate conventional crop lifters below the cutting height to lift these downed stalks.
Crop lifters interfere somewhat with normal operations of the header when harvesting taller crops with the header raised a substantial distance above the ground. During turns in particular, because the crop lifters generally extend a considerable distance ahead of the header, some crop stalks are pushed over and not cut. It is common practice therefore to remove the crop lifters when using the header on taller crops. In view of this, and the further requirement as discussed above to remove the lifters for repair and replacement, there is also considerable prior art directed to providing a crop lifter that is easily installed and removed.
U.S. Pat. No. 3,579,967 to Schumacher discloses a quick attachment mechanism for a crop lifter. A rear end of a springy arm of the crop lifter defines a notch that fits into an annular groove in a nut that attaches the guard to the header. The extreme rear end of the notched portion is bent down, such that the notch can only be inserted into the groove when the front end of the arm is tilted downward. After insertion, the front end of the arm is raised, and a hook is placed over the guard finger to lock the arm in tension and in the raised position. With the arm so raised, the bent portion at the rear of the arm prevents the arm from moving forward and disengaging the grooved nut.
U.S. Pat. Nos. 4,295,328 and 6,442,919 and U.S. Patent Application Publication 2003/0005678 of Schumacher disclose quick attachment mechanisms for crop lifters that use the bent rear notch and provide alternate mechanisms using springs, clips and the like to hold the arm in the raised position by releasably securing the arm to the guard finger.
Canadian Patent Numbers 548,220 to A. Claas and 719,825 to R. Claas disclose a quick attachment mechanism for a crop lifter that attaches only to the guard finger with a spring biased clamp.